THE AMPHIBIA OF OKLAHOMA 



fall data are taken from the United States Weather Bureau, University Sta- 

 tion, Norman. 



One unsuspected relationship was brought out for the xeric form, Bufo 

 cognatus. On the 13th and 14th, 2.75 in. of rain is recorded, but the tempera- 

 ture was near freezing. During the next two days a drizzle with showers 

 brought a total of 1.08 in. more, while the temperature still remained low. 

 The animals bred in large numbers the night of the 17th at 13°C. This sug- 

 gests that B. cognatus, like the prairie spadefoot, Scaphiopus bombijrons 

 (Bragg and Smith, 1942), may receive the stimulus for breeding by heavy 

 rainfall at low temperatures and have a delayed response to this as the tem- 

 perature rises above the critical point. 



Note also that S. bomhijrons is recorded as breeding on the 14th, but not 

 on the 13th. This was a very small congress at just about the critical point of 

 temperature. A large congress of this species occurred with B. cognatus on the 

 17th, just as was expected from former observations. 



The data presented, therefore, support my former general statements 

 given without many supporting data, as to the breeding patterns and they 

 further indicate that breeding periods are distinct from breeding seasons. 



Literature Cited 



Bragg, Arthur N. 1940. Observations on the ecology and natural history of Anura I. Habits, 

 habitat, and breeding of Btifo cognatus Say. Amer. Nat. 74:322—349 and 424-435. 



. 1944-45. The Spadefoot Toads in Oklahoma with a summary of our knowledge 



of the group. Amer. Nat. 79:517-533 and 80:52-72. 



1946. Some salientian adaptations. Great Basin Nat. 7:11—15. 



Bragg, A. N., and Charles C. Smith. 1943. Observation etc. IX. Notes on breeding behavior 

 in Oklahoma. Great Basin Nat. 3:33-50. 



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